Wait. Is this primarily a collection or not?

Is this a collection of stories or a main story with several extras/side-stories? Because it's multi-volume... So I'm confused about whether each volume is a collection of independent stories or whether there is some plot linking them. I'd like to know before I start reading. Thanks.

Hello, these are a collection of one-shots which all revolve around the same theme ("A rose colored tomorrow"). Later on, there are one-shots that tie in together (for example, Volume 2 has four one-shots with recurring characters), but generally they can be read seperately without affecting the overall message of the story.